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Date: Thu, 8 Jun 2017 13:54:48 +0200
From: Jiri Olsa <jolsa@redhat.com>
To: David Carrillo-Cisneros <davidcc@google.com>
Cc: linux-kernel@vger.kernel.org, Peter Zijlstra <peterz@infradead.org>,
        Ingo Molnar <mingo@redhat.com>,
        Arnaldo Carvalho de Melo <acme@kernel.org>,
        Alexander Shishkin <alexander.shishkin@linux.intel.com>,
        Andi Kleen <ak@linux.intel.com>, Simon Que <sque@chromium.org>,
        Wang Nan <wangnan0@huawei.com>, Jiri Olsa <jolsa@kernel.org>,
        He Kuang <hekuang@huawei.com>, Masami Hiramatsu <mhiramat@kernel.org>,
        Stephane Eranian <eranian@google.com>, Paul Turner <pjt@google.com>
Subject: Re: [PATCH v3 15/15] perf header: add event desc to pipe-mode header
Message-ID: <20170608115448.GD29151@krava>
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 <20170606070722.35213-16-davidcc@google.com>
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On Tue, Jun 06, 2017 at 12:07:22AM -0700, David Carrillo-Cisneros wrote:

SNIP

> diff --git a/tools/perf/util/header.c b/tools/perf/util/header.c
> index 6c1963e5bf10..c91acd5b0838 100644
> --- a/tools/perf/util/header.c
> +++ b/tools/perf/util/header.c
> @@ -66,6 +66,7 @@ struct feat_fd {
>  	void			*buf;	/* Either buf != NULL or fd >= 0 */
>  	ssize_t			offset;
>  	size_t			size;
> +	struct perf_evsel	*events;
>  };
>  
>  void perf_header__set_feat(struct perf_header *header, int feat)
> @@ -1353,10 +1354,15 @@ static int __desc_attr__fprintf(FILE *fp, const char *name, const char *val,
>  
>  static void print_event_desc(struct feat_fd *ff, FILE *fp)
>  {
> -	struct perf_evsel *evsel, *events = read_event_desc(ff);
> +	struct perf_evsel *evsel, *events;
>  	u32 j;
>  	u64 *id;
>  
> +	if (ff->events)
> +		events = ff->events;
> +	else
> +		events = read_event_desc(ff);

can you read from ff at this point in print callback?

jirka